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Google reCAPTCHA using PHP and jQuery.

A CAPTCHA is a program that protects websites against bots by generating and grading tests that humans can pass but current computer programs cannot.
It is usually a graphic image with a series of distorted letters on an equally distorted or multicolored background.
Google has released the new reCAPTCHA. Using reCAPTCHA users can prove they are human without solving a CAPTCHA.

Steps for google reCAPTCHA implementation.

1. Create a secure key and site key
Register your site at Google from here –
2. Html Code

Now first of all include Google reCAPTCHA javascript library.
<script src="" async defer></script>

Now in form body section add reCAPTCHA DIV element

<form action="" method="POST">
    <input type="text" name="name" value="" />
    <input type="text" name="email" value="" />
    <textarea type="text" name="message"></textarea>
    <div class="g-recaptcha" data-sitekey="9LDDpf0eVtMZY6kdJnGhsYYY-5ksd-W"></div>
    <input type="submit" name="submit" value="SUBMIT">

Now replace data-sitekey attribute value to your sitekey.

Now for server side validation. I have used PHP script.

if(isset($_POST['submit']) && !empty($_POST['submit'])){
    if(isset($_POST['g-recaptcha-response']) && !empty($_POST['g-recaptcha-response'])){
        //your site secret key
        $secret = '6LfOtiDDDDDDDOv5_4vb4tocXZXASDFDW';
        //get verify response data
        $verifyResponse = file_get_contents(''.$secret.'&response='.$_POST['g-recaptcha-response']);
        $responseData = json_decode($verifyResponse);
            // After success statement
            $succMsg = 'Your contact request have submitted successfully.';
            $errMsg = 'Robot verification failed, please try again.';
        $errMsg = 'Please click on the reCAPTCHA box.';
Now How to Validate using jQuery Validatation method

1. Replace Form reCAPTCHA element with 

<input type="hidden" class="hiddenRecaptcha required" name="hiddenRecaptcha" id="hiddenRecaptcha">
<div class="g-recaptcha" data-sitekey="{YOUR-SITE-KEY-HERE}"></div>

2. Now add validation Rule

   ignore: ".ignore",
   rules: {
       "hiddenRecaptcha": {
           required: function() {
               if(grecaptcha.getResponse() == '') {
                   return true;
               } else {
                   return false;

Advantages of CAPTCHA

  • Preventing Comment Spam in Blogs.
  • Protecting Website Registration.
  • Protecting Email Addresses From Scrapers.
  • Online Polls.
  • Preventing Dictionary Attacks.
  • Search Engine Bots.
  • Worms and Spam.


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